Fernando Bobillo Miguel Delgado Juan Gómez-Romero Crisp Representations and Reasoning for Fuzzy Ontologies. 501-530 2009 17 International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 4 http://dx.doi.org/10.1142/S0218488509006121 db/journals/ijufks/ijufks17.html#BobilloDG09